Multimode Analysis Draws Complete Tissue Picture

Desorption electrospray ionization (DESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging can be combined with histological staining for a three-pronged approach to analyzing single tissue samples, scientists report (Anal. Chem., DOI: 10.1021/ac202016x). The two types of mass spec imaging provide chemical information, whereas histological staining provides sample morphology information. Usually, these three analyses can’t be performed on the same tissue slice because the necessary conditions are so different. R. Graham Cooks of Purdue University, Nathalie Y. R. Agar of Harvard Medical School, and coworkers developed a method that lets them obtain all three images. The researchers first image lipids in the sample with DESI; then they apply a sinapinic acid matrix and image the proteins with MALDI; finally, they wash off the MALDI matrix, add hematoxylin and eosin histological stains, and record an optical image. With this sequential analysis, chemical information can be unambiguously matched to morphological information. The researchers demonstrated the method using tissue slices from mouse brains and human brain tumors.